Hello,
What semantics are you using for recursive modules? As far as I see, if you take a least fixed point semantics (e.g. as described in "A Formal Specification for the Haskell 98 Module System", http://yav.github.io/publications/modules98.pdf ) this program is incorrect as the module does not export anything.
While this may seem a bit counter intuitive at first, this semantics has the benefit of being precise, easily specified, and uniform (e.g it does not require any special treatment of the " current " module). As an example, consider the following variation of your program, where I just moved the definition in a sperate (still recursive) module:
module A (M.x) where
import B as M
module B (M.x) where
import A as M
x = True
I think that it'd be quite confusing if a single recursive module worked differently then a larger recursive group, but it is not at all obvious why B should export 'x'. And for those who like this kind of puzzle: what should happen if 'A' also had a definition for 'x'?
Iavor
You don't need a new language construct, what i do is:module AnnoyinglyLongModuleName (M.length, M.null) whereimport AnnoyinglongLongModuleName as MI think ghc would need to be extended a little to make this convienient as it doesn't handle recursive module imports as transparently.JohnOn Mon, Sep 29, 2014 at 8:47 AM, Brandon Allbery <allbery.b@gmail.com> wrote:
I think if I wanted this syntax, I'd go for:module AnnoyinglyLongModuleName as M where ...--brandon s allbery kf8nh sine nomine associatesunix, openafs, kerberos, infrastructure, xmonad http://sinenomine.net
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John Meacham - http://notanumber.net/
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